Hose clamps, such as those used for connecting a hose to a pipe nipple, are mostly made with such a predetermined rated diameter that the inner surface of the clamping band contacts the hose throughout the entire periphery without gaps and a continuously uniform sealing pressure is achieved between the hose and the pipe nipple.
Known from EP 0 697 554 A and WO 2007/128334 A are hose clamps in which the inner end portion of the clamping band is formed with a tongue, which has a width smaller than the full width of the clamping band, and hooks for closing the hose clamp, and the outer end portion has openings for engaging the hooks and an ear-like tightening device for tightening the hose clamp around an object to be clamped. Further provided in the outer end portion of the clamping band is an arcuate band portion for receiving the tongue, the arcuate band portion being cut free from the clamping band by longitudinal cuts, which leave lateral band webs and starting at a step formed in the clamping band, the step corresponding to the thickness of the clamping band.
The length of the tongue is so designed that in a closed, not yet tightened condition of the hose clamp, the tip of the tongue traverses the step by some length and is guided by the lateral band webs, whereas in the tightened condition, the full band width must not reach the step. Thus, the length of the tongue must be at least equal to the peripheral difference between the non-tightened and the tightened hose clamp.
EP 0 657 676 A2 discloses a hose clamp in which the outer clamping band portion has an elongated window with a stop edge, and the inner clamping band portion has a tongue with a series of hooks, one of which engages the stop edge in the tightened condition of the hose clamp. While this hose clamp is principally usable for a variety of diameters, there is always an area left between the inner end of the tongue and the outer end of the window where the hose is supported by only by the narrower tongue and the sealing pressure is correspondingly reduced.
Otherwise, screw clamps are known, e.g., from EP 0 523 600 A, as diameter adjustable clamps which are substantially more expensive to manufacture and to mount.